I've tried two of these cables for a USB3.0 external hard drive - they don't work. The hard drive does not turn on and is not recognized. Maybe they are good for phone charging, but they don't work for transferring data and powering external hard drives. Amazing design, perfect length and style and the company sent me a replacement for free so support but now I've spent more time on it than it's worth. Pros - Perfect length - Cool styling - Gold plated connectors - Great customer service Cons - Doesn't Doesn't power my external hard drive - Doesn't transfer data - Doesn't work with hard drives